Electric switch device



N. L. FREEMAN ELECTRIC SWI'TCH DEVICE Filed Oct. 7, 1945 2 Sheets-Sheet 1 FIG. I..-

INVENTOR Nevye/l L. Freeman BY ATT' NEY Patented May 21, 1946 ELECTRIC swrron nnvrca Newell L. Freeman, Schenectady, N, Y., assignor to American Locomotive Company, New York, N. Y., a corporation of New York Application October 7, 1943, Serial No. 505,290

4 Claims.

This invention relates to electric switch devices and more particularly to an interlock for a pair of switches.

It is well known to provide an electric switch device including two master switches for opening and closing two circuits. These two circuits may be independent of each other, as in the case where each supplies current to 'a separate mechanism and where there is a certain predetermined order in which the two mechanisms should be operated. Or the two circuits may cooperate as where one is a high voltage circuit and the other a low volt-1 age circuit, the circuits having a common portion and there being a certain predetermined order in which the circuits should be opened and closed. In either case, the inadvertent operation of the switches in the wrong order would result in damage. The present invention is directed to providing an interlock for the switches preventing such inadvertent operation in the wrong order.

An object of the present invention is to provide an interlock for a pair of switches ,so that their operation must be. in a predetermined order.

Other and further objects of this invention will appear from the following description, the accompanying drawings and the appended claims.

Referring to the drawings forming part of this application, Figure 1 is a plan of an electric switch device embodying the present invention,

an open circuit position or one of the switches being indicated in dot and dash lines; Fig. 2 is a side elevation of the device of Fig. 1, an open circuit position of the switches and interlock being indicated in dot and dash lines; Fig. 3 is a vertical central section through the switch at the right in Fig. 1, parts being shown in full; Fig. 4 is a vertical central section of the upper portion of the switch shown in Fig. 3, taken at right angles to the section of Fig. 3, parts being omitted; Fig. 5 is a section on the line V--V of Fig. 4, parts being broken away; and Fig. 6 is a diagrammatic layout of the switch device and electric circuits in which it may be employed, the circuits being shown open.

The electric switch device is indicated generally in the drawings by the reference numeral 1. For the purposes of description and illustration it will be assumed that the device is to be employed with one of its switches operating a high voltage circuit and the other of its switches operating a low voltage circuit, and the following description will be so limited. However, it will be understood that the switch device is adapted for use with two independent circuits of any desired voltage, no change in the structure of the device being necessary.

The device includes two master switches 2 and 3 which are identical in structure except for the inclusion of slots in the handle of switch 3 for coaction with the interlock, as will presently appear. Switch 2-is for a low voltage circuit and switch 3 is for a high voltage circuit. For instance, switch 2 may be a 12 volt switch while switch 3 may be a 24 volt switch, and they will be so considered in the iollowing description.

Each switch includes a case 4 from which extend orificed ears 5. Bolts 8, extending through the orifices of the ears 5, secure the case to a plate I. The switches are arranged side by side with the orifices of the ears all in a line. 4

Case 4 is V-shaped in vertical cross section providing two inclined :bottom walls 8 and a horizontal top wall 3. An orifice I0 is formed in each wall 8. A flanged insulating washer I I is disposed in the case adjacent each orifice lo, the flange extendingthrough the orifice, adjacent an insulating washer l2 engaging the outer facebf the adjacent wall 8. 'A threaded terminal post l3 having a head within the case, extends through the adjacent washers and is. secured in place by a nut l4. Nuts I5 (Fig. 2) are for securing wires of the electric circuit to the posts l3 in the usual manner.

A threaded flanged orifice I6 is formed centrally in the wall 9 and a barrel I! is threaded therein and extends upwardly therefrom. An annular flange l8 extends inwardly from the wall of the barrel a short distance below its top edge, and two diametrically opposed tongues !9 also extend inwardly from this portion of the barrel, the tongues extending from the flange to the top edge of the barrel.

The device further includes a switch member 20, having a handle 2| and a stem 22. The stem is disposed in the barrel and case and has a reduced square portion at the bottom on which is mounted a contact piece 23 which maybe insulated from the stem 22 in a manner similar to the aforesaid insulation of the posts l3. Nuts 24 secure piece 23 to the stem. A dowel 25, sup porting a washer 26, extends through the stem adjacent the bottom of the barrel and a conical spring 21 is disposed in the barrel, surrounding the stem and bearing at its top against the flange l8 and at its bottom against the washer 26. Spring 21 is under compression tending to force the stem downward. The upper end of the stem is square and fits in a square recess 28 formed in the handle 2|. A screw 29 secures the handle and stem together.

The handle has an outer cylindrical wall 30 which surrounds the top portion of the barrel and an inner slotted cylindrical wall 3| which is disposed within the top portion of the barrel. Wall 3| has two diametrically opposed long depending portions 32 between which are short depending portions provided with shallow slo'ts 33, there being one slot adjacent each edge of the portions 32, these edges providing abutments for the tongues l9, opposed slots 33 forming a diametral of switch 2 with wire 39.

pair for simultaneous coaction with tongues :I9. Two diametrically opposed deep slots 34 are formed in the wall 3I at right angles to the portions 32. Slots 33 and 34 are for coaction with the tongues I9. As will later more fully appear when the tongues are disposed in the slots 34,

the switch is closed. Slots 33 are employed to hold the switch open, there being slots 33 on both sides of each slot 34 so that the handle, turned in either direction, will effect engagement of slots 33 with the tongues I9.

Wall 30 of switch 3 at the side thereof adjacent switch 2, when switch 3 is in closed position, is provided with two notches 35 ninety degrees apart, each being in line with a diametral pair of slots 33, so that a notch 35 can be brought into an operative position, as will later more fully appear, by rotation of the handle forty-five degrees in either direction. Switch 3 differs from switch 2 only by the inclusion of the notches 35.

The electric circuits are shown in Fig. 6. A 24 volt battery A is grounded at one end and is connected at the other end by a wire 36 to one post I3 of switch 3. The other post l3 of switch 3 is connected by a wire 31 to a dynamotor 38. A wire 39 connects the dynamotor with radio tubes 40, which are grounded, thus completing one circuit. A wire 4I leads from the post I3 of switch 3 (connected to wire 31) for connection with other equipment, (not shown).

The other circuit includes a wire 42 connected at one end to the battery at an intermediate point thereof, and at the other end to one post l3 of switch 2. A wire 43 connects the other post I3 Thus wire 43 is also connected to the tubes 40, wire 39 and tubes 40 being common to both circuits.

The circuits described are for the purpose of illustration only, the switch device being adapted for use with various different circuits. The circuits described are two circuits ordinarily employed in a tank (armed tank for warfare), wherein it is necessary to have a battery of a higher voltage than some apparatus connected therewith is adapted to withstand if subjected abruptly to the full voltage of the battery. For instance, in the aforesaid tank, it is necessary to have a 24 volt battery for supplying current to various apparatus, one of which is a radio having tubes which would be injured if suddenly supplied with or cut oil from the full 24 volts. Thus the two switches are employed so that the radio will be connected up with a 12 volt circuit prior to connection with a 24 volt circuit, and will be disconnected from the 24 volt circuit prior to disconnection from the 12 volt circuit.

The operation of the switch device to control the circuits is as follows: Assuming the switches are both open as shown in Fig. 6, switch 2 will be closed first, thereby connecting the radio up with the battery by a 12 volt circuit. Thereafter the switch 3 is closed, permitting the 24 volts to fiow to the dynamotor and to the radio. However, as the 12 volt circuit is closed first, there is no abrupt subjecting of the radio tubes to the full 24 volts. Similarly, when it is desired to open the circuits, the 24 volt switch is opened first so that there will not be a sudden cut-off of the full 24 volts from the radio tubes.

When it is desired to open a switch from closed position as shown in Fig.3, it is necessary to pull the handle 2I upward, thus raising the contact piece 23 and thereby breaking its contact with the posts I3. Handle 2| is pulled upward until the tongues I9 and slots 34 are disengaged (see ends.

switch 2. dot and dash lines, in Fig. 2), and then turned until abutment edges of portions 32 engage tongues I9 at which time two diametrically opposed slots 33 will be in alignment with the tongues I9. Upon then releasing the handle, the spring 21 will pullthe handle downward (see switch 3, dot and dash lines, in Fig. 2), the tongues I9 then engaging the two slots 33 in registry therewith, thereby locking the handle in switch open position to prevent inadvertent closing of the switch.

If the 24 volt switch should be inadvertently closed before or opened after the 12 volt switch, the radio tubes 43 would be abruptly subjected to the action of the full 24 volts. The present invention is directed toward preventing such an inadvertent action, and in accordance therewith a switch interlock, indicated in the drawings by the reference numeral 44, is provided.

The interlock 44 includes a clevis 43, disposed between the switches 2 and 3, the base of the clevis being oriflced and secured to the plate 1 by the inner bolts 3, the clevis further having upstanding wings 46 in which are formed aligned horizontal orifices 41 disposed adjacent switch 3. A lock member 43 is pivotaily connected to the clevis by a pin 49 which extends through a horizontal bore in the lowermost corner of the member 48 adjacent the switch 3 and through the orifices 41 of the clevis and therebeyond at both The ends of the pin are orificed and cat-- ter pins 50 secured therein.

The lock member 43 further includes a bottom forked plate-like part 5| which extends from below the pin 49 to switch 2, one branch of the fork being disposed on each side of the barrel I1 of switch 2 immediately below and in engagement with the cylindrical wall 30 of the handle 2| thereof. A vertical plate-like part 52 extends upwardly above the pin 49 toward the cylindrical wall 30 Of the switch 3 and therefrom toward switch 2. It has a lock part 53 of a width adapting it to engage either of the notches, 35, and a finger 54 overlapping and in engagement with the top of the handle 2i of switch 2 for coaction therewith.

Referring more particularly to Fig. 2, the switch closed position of the handles of switches 2 and 3 and of the interlock are shown in full lines at which time part 53 is opposed to the exterior side face of wall 30 of the handle of switch 3, between notches 35, with very little clearance therebetween. Thus the interlock prevents handle 2I of switch 2 from being raised to open switch 2, as any such raising of this handle would raise the finger 54 and rock part 53 toward switch 3. which is prevented by the abutting of part 53 against wall 30 of switch 3. Therefore the handle of switch 3 must be raised until tongues I3 and slots 34 are disengaged and then turned until one of the notches 35 isin line with part 53, at which time the tongues I9 will be in engagement with their abutments and the corresponding pair of slots 33. Switch 3 will then be open and switch 2 can then be opened. Opening of switch 3 leaves only the 12 volt circuit closed and therefore the radio tubes can not be subjected to an abrupt change from 24 volts to no current at all.

When the handle of switch 3 has been raised and turned so that the tongues I3 thereof coact with the slots 33 thereof, one of the notches 33 is in line with part 53, as aforesaid, and handle 2I of switch 2 can then be raised, opening the 12 volt circuit, part 53 then rocking about the pin 49 until it is in the notch 35, as shown in the dot-dash lines of Fig. 2. Both switches will then be open, and part 53 will coact with the engaged notch 35 of switch 3 to prevent handle 2! of switch 3 from being turned to close the 24 volt circuit. Thus the interlock prevents the 24 volt switch 3 from being closed until after the 12 volt switch 2 has been closed.

Thus it will be seen from the foregoing that by the use of the interlock, switch 2 (low voltage) can be opened only after switch 3 (high voltage) has been opened, and further switch 3 can be closed only after switch 2 has been closed. In theseregards, the device of the present invention provides a positive lock for the circuits.

While there has been hereinbefore described an approved embodiment of this invention, it will be understood that many and various changes and modifications in form, arrangement of parts and details of construction thereof may be made without departing from the spirit of the invention, and that all such changes and modifications as fall within the scope of the appended claims are contemplated as a part of this invention.

The invention claimed and desired to be secured by Letters Patent is:

1. An electric switch device comprising two.

manually-operable switches; and an interlock for said switches, each of said switches having a separate operating means, one of said means including a member rotatable to two positions, said member having an exterior face and a slot, said member face being active at one of said positions when its switch is in closed position and said member slot being active at the other of said positions when its said switch is in open position, said interlock having a part coactable with said member face and slot respectively when at their said positions, said interlock having another part coactable with the other of said means, said interlock parts operating to control said switches, said parts simultaneously operating, when both said switches are in closed position. to leave said member-including switch free to be opened while holding the other of said switches from being opened until said member-including switch is opened, said parts further simultaneously operating, when both said switches are in open posiopened until said member-including switch is opened, said parts further simultaneously operating, when both said switches are in open positions, to leave said other switch free to be closed while holding said member-including switch from being closed until said other switch is closed.

3. An electric switch device comprising two manually-operable switches; and an interlock for said switches rockable to two positions, each of said switches having a separate operating means, one of said means including a member rotatable to two positions, said member having an exterior side face and a side slot, said member face being active at one of said member positions when its switch is in closed position and said member slot being active at the other of said member positions when its said switch is in open position, said interlock having a part coactable with said member face and slot respectively when at their said member positions, the other of said means including a member having an exterior top face, said interlock having another part coactable with said top face, said interlock parts operating to control said switches, said parts simultaneously operating, when both said switches are in closed positions and said interlock is in one of its said rocked positions, to leave said rotatable-memberincluding switch free to be opened while holdin the other of said switches from being opened tions, to leave said other switch free to be closed while holding said member-including switch from being closed until said other switch is closed.

2. An electric switch device comprising two manually-operable switches; and an interlock for said switches, each of said switches havinga separate rotatable operating means, a spring yieldingly holding its switch in closed position and means for holding its switch in open position and for preventing rotation of its switch-operating means when its switch is in open and in closed positions, one of said operating means including a member rotatable therewith to two positions, said member being active at one of its said positions when its switch is in closed position and active at the other of its said positions when its said switch is in open position, said interlock having a part ccactable with said member when at its said positions, said interlock having another part coactable with the other of said operating means, said interlock parts operating to control said switches, said parts simultaneously operating, when both said switches are in closed positions, to leave said member-including switch free to be opened while holding the other of said switches from being until said rotatable-member-including switch is opened, said parts further simultaneously operating, when both said switches are in open positions and said interlock is in the other of its said rocked positions, to leave said other switch free to be closed while holding said rotatable-member-ineluding switch from being closed until said other switch is closed.

4. An electric switch device comprising two switches; and a separate interlock, each of said switches having a separate operating means manually movable in the direction of its axis to switch-closed and switch-open positions, one of said means being manually rotatable about its said axis to two active positions, one when its switch is in closed position and the other when its switch is in open'position, said interlock bein rockable about a fixed axis to two switch-locking positions, said interlock, when in one of its said rocked positions, coacting with said rotatable operating means when at one of its said rotated positions, said interlock, when in the other of its said rocked positions coacting with said rotatable operating means when at the other of its said rotated positions, said interlock being further coactable with the other of said operating means, said interlock coacting simultaneously with both said switch-operating means, when both said switches are in closed position, to leave said rotatable operating means free to be axially moved to its switch-open position while holding said other of said operating means from being axially moved to its switch-open position until said rotatableoperating-means switch is opened, said interlock 

